Wednesday, 30 September 2015

How to Use Noise Removal with Audacity for Audio Books

A soundproof room is not always possible when living next to a busy road or beneath the flight path of holiday makers whilst recording your audio book. But producing clean sound files demand a low noise floor. This means lack of background noise, whether it comes from the humming of a fridge or the hush of traffic outside. Noise removal is the answer, but beware! Use with caution, or your sound files will be ruined. Here’s how to use noise removal when recording audio books.

How to Use Noise Reduction for Audio Books

Using Noise Removal
Once you have finished recording your session, find a section of recording where nothing is going on, a flat line on the wave pattern. Highlight it and listen to what is there. Even apparent silence has noise. Keep selecting a section of quiet recording until you can find the absolute noise floor, no breaths, no shuffling, just the sound of the room. This might be a continuous low rumble or a slight hissing sound. If unsure, amplify the section and listen out for anything other than the noise floor. Select a different section if necessary.

Noise Reduction Tips

Undo amplify if you have amplified it and then select ten to thirty seconds or so of flat line recording of the noise floor. Now click on ‘effects’ on Audacity and select ‘noise reduction’.

Now click on ‘get noise profile’ (as shown on image). A dialogue box will come up. You will notice three sliders, where you can choose how sensitive the noise removal will be. I will select maximum reduction and maximum sensitivity, as I want absolute silence between my vocals. Click OKand the box will disappear after recording the sound profile.

Select the entire recording by pressing ctrl and ‘a’, then select ‘noise removal’ again, then OK. Wait a few seconds while the noise reduction is in progress.

Finding Noise Profile of a Room
Important: listen to the recording once the noise reduction has taken place, to ensure your voice still sounds OK. This is why I will exercise noise reduction with utmost caution. If the sound frequencies have been stripped bare by noise reduction, this can result in a chirpy sound to your voice. If this happens, you can always ‘undo’ noise removal and select a different section of recording before repeating noise removal.

Audio Book Recording

In my experience, selecting a recording with a low noise floor, where just a background hush is going on, will not affect the vocals. You should result in a nice, clean recording where only your voice can be heard.

Once removing the general background noise of a room, you can also go through the recording and perform selective noise removal if an aeroplane happened to make a transit during a particular section of recording. This can happen without notice. Remember, you have to repeat the noise removal so that it will filter out the noise desired.

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